Typically, a toggle type mold clamping apparatus which is mounted on an injection molding machine comprises a double toggle link type toggle mechanism having a pair of toggle sections (toggle links) which are disposed between a rear platen and a movable platen of the injection molding machine and which are symmetric with each other with respect to an axis of the clamping apparatus in the vertical direction. The toggle sections are coupled to each other by means of a crosshead which is threadedly engaged with a ball screw disposed on the axis of the mold clamping apparatus. The mold clamping apparatus is arranged so that, as the crosshead is moved toward the movable platen along the ball screw with rotation of the ball screw, two links of each of the toggle sections for generating a pressing force gradually expand to be switched from a state in which these links are bent to another state in which the links are stretched to establish a straight line relationship therebetween, so as to apply a pressing force onto the movable platen. With a mold clamping apparatus of the kind having a pair of toggle sections which are disposed symmetrically, it is possible to apply the pressing force generated by the toggle mechanism to the movable platen uniformly over the entire surface of the movable platen to a considerable extent. However, since primary parts of the mold clamping apparatus such as the ball screw, crosshead, etc., are disposed and concentrated on the axis of the clamping apparatus, flexure of the toggle mechanism is liable to occur, resulting in poor uniformity of the pressing force applied to the movable platen. Moreover, when flexure of the ball screw occurs due to the weight of the ball screw and the weight of the crosshead and the like, forces resulting from this flexure are exerted on the upper and lower toggle sections, which are separated from each other in the vertical direction of the clamping apparatus, in opposite directions from each other with respect to operational phases of these toggle sections. In this connection, the pressing force applied to the movable platen lacks uniformity. Consequently, parallelism between the rear platen and the movable platen deteriorates, as does the parallelism between the movable platen and the front platen. Accordingly, a guide pin disposed between mold halves respectively mounted on these platens is liable to be damaged, when a mold is employed.